This is interesting to me, because this is a conversation that he and I have had a number of different times, over a number of different specifics (was that an oxymoron?).

The obvious one is that oysters are shellfish and thus not Kosher, but plenty of Jewish women wear pearls. I tend to agree with you and your interpretation that not Kosher should = not Kosher, and that if the oyster meat is out, then the pearls should be too.

I think the most recent version of this conversation happened when I went to hang out with Leo and his pig. aaronbenedict's answer then was that it would not be proper for a Jew to reap financial benefit from pigs, whether it was killing them to eat, or breeding them as pets. Whether or not it was OK to play with someone else's pet pig was more nebulous. But he conceded on the whole topic that he wasn't completely certain.

I've emailed a link to your reply to him. Hopefully he'll give a more educated answer than this one.

I guess that the best way to understand kosher in the context of food is that of a diet that you need to be on. Using that as a guide, wearing the clothing from something that isn't Kosher is fine. The word "kosher" has since been used to define anything that is permissible, but that's really not the proper usage. Kind of like using the word ironic when something isn't. Keeping kosher is one of the 613 commandments just like the commandment not to wear clothes that are made of shatnes.